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+//===--- JSONTransport.cpp - sending and receiving LSP messages over JSON -===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "Logger.h"
+#include "Protocol.h" // For LSPError
+#include "Transport.h"
+#include "llvm/Support/Errno.h"
+
+using namespace llvm;
+namespace clang {
+namespace clangd {
+namespace {
+
+json::Object encodeError(Error E) {
+ std::string Message;
+ ErrorCode Code = ErrorCode::UnknownErrorCode;
+ if (Error Unhandled =
+ handleErrors(std::move(E), [&](const LSPError &L) -> Error {
+ Message = L.Message;
+ Code = L.Code;
+ return Error::success();
+ }))
+ Message = llvm::toString(std::move(Unhandled));
+
+ return json::Object{
+ {"message", std::move(Message)},
+ {"code", int64_t(Code)},
+ };
+}
+
+Error decodeError(const json::Object &O) {
+ std::string Msg = O.getString("message").getValueOr("Unspecified error");
+ if (auto Code = O.getInteger("code"))
+ return make_error<LSPError>(std::move(Msg), ErrorCode(*Code));
+ return make_error<StringError>(std::move(Msg), inconvertibleErrorCode());
+}
+
+class JSONTransport : public Transport {
+public:
+ JSONTransport(std::FILE *In, llvm::raw_ostream &Out,
+ llvm::raw_ostream *InMirror, bool Pretty, JSONStreamStyle Style)
+ : In(In), Out(Out), InMirror(InMirror ? *InMirror : nulls()),
+ Pretty(Pretty), Style(Style) {}
+
+ void notify(StringRef Method, json::Value Params) override {
+ sendMessage(json::Object{
+ {"jsonrpc", "2.0"},
+ {"method", Method},
+ {"params", std::move(Params)},
+ });
+ }
+ void call(StringRef Method, json::Value Params, json::Value ID) override {
+ sendMessage(json::Object{
+ {"jsonrpc", "2.0"},
+ {"id", std::move(ID)},
+ {"method", Method},
+ {"params", std::move(Params)},
+ });
+ }
+ void reply(json::Value ID, Expected<json::Value> Result) override {
+ if (Result) {
+ sendMessage(json::Object{
+ {"jsonrpc", "2.0"},
+ {"id", std::move(ID)},
+ {"result", std::move(*Result)},
+ });
+ } else {
+ sendMessage(json::Object{
+ {"jsonrpc", "2.0"},
+ {"id", std::move(ID)},
+ {"error", encodeError(Result.takeError())},
+ });
+ }
+ }
+
+ Error loop(MessageHandler &Handler) override {
+ while (!feof(In)) {
+ if (ferror(In))
+ return errorCodeToError(std::error_code(errno, std::system_category()));
+ if (auto JSON = readRawMessage()) {
+ if (auto Doc = json::parse(*JSON)) {
+ vlog(Pretty ? "<<< {0:2}\n" : "<<< {0}\n", *Doc);
+ if (!handleMessage(std::move(*Doc), Handler))
+ return Error::success(); // we saw the "exit" notification.
+ } else {
+ // Parse error. Log the raw message.
+ vlog("<<< {0}\n", *JSON);
+ elog("JSON parse error: {0}", llvm::toString(Doc.takeError()));
+ }
+ }
+ }
+ return errorCodeToError(std::make_error_code(std::errc::io_error));
+ }
+
+private:
+ // Dispatches incoming message to Handler onNotify/onCall/onReply.
+ bool handleMessage(llvm::json::Value Message, MessageHandler &Handler);
+ // Writes outgoing message to Out stream.
+ void sendMessage(llvm::json::Value Message) {
+ std::string S;
+ llvm::raw_string_ostream OS(S);
+ OS << llvm::formatv(Pretty ? "{0:2}" : "{0}", Message);
+ OS.flush();
+ Out << "Content-Length: " << S.size() << "\r\n\r\n" << S;
+ Out.flush();
+ vlog(">>> {0}\n", S);
+ }
+
+ // Read raw string messages from input stream.
+ llvm::Optional<std::string> readRawMessage() {
+ return Style == JSONStreamStyle::Delimited ? readDelimitedMessage()
+ : readStandardMessage();
+ }
+ llvm::Optional<std::string> readDelimitedMessage();
+ llvm::Optional<std::string> readStandardMessage();
+
+ std::FILE *In;
+ llvm::raw_ostream &Out;
+ llvm::raw_ostream &InMirror;
+ bool Pretty;
+ JSONStreamStyle Style;
+};
+
+bool JSONTransport::handleMessage(llvm::json::Value Message,
+ MessageHandler &Handler) {
+ // Message must be an object with "jsonrpc":"2.0".
+ auto *Object = Message.getAsObject();
+ if (!Object || Object->getString("jsonrpc") != Optional<StringRef>("2.0")) {
+ elog("Not a JSON-RPC 2.0 message: {0:2}", Message);
+ return false;
+ }
+ // ID may be any JSON value. If absent, this is a notification.
+ llvm::Optional<json::Value> ID;
+ if (auto *I = Object->get("id"))
+ ID = std::move(*I);
+ auto Method = Object->getString("method");
+ if (!Method) { // This is a response.
+ if (!ID) {
+ elog("No method and no response ID: {0:2}", Message);
+ return false;
+ }
+ if (auto *Err = Object->getObject("error"))
+ return Handler.onReply(std::move(*ID), decodeError(*Err));
+ // Result should be given, use null if not.
+ json::Value Result = nullptr;
+ if (auto *R = Object->get("result"))
+ Result = std::move(*R);
+ return Handler.onReply(std::move(*ID), std::move(Result));
+ }
+ // Params should be given, use null if not.
+ json::Value Params = nullptr;
+ if (auto *P = Object->get("params"))
+ Params = std::move(*P);
+
+ if (ID)
+ return Handler.onCall(*Method, std::move(Params), std::move(*ID));
+ else
+ return Handler.onNotify(*Method, std::move(Params));
+}
+
+// Tries to read a line up to and including \n.
+// If failing, feof() or ferror() will be set.
+bool readLine(std::FILE *In, std::string &Out) {
+ static constexpr int BufSize = 1024;
+ size_t Size = 0;
+ Out.clear();
+ for (;;) {
+ Out.resize(Size + BufSize);
+ // Handle EINTR which is sent when a debugger attaches on some platforms.
+ if (!llvm::sys::RetryAfterSignal(nullptr, ::fgets, &Out[Size], BufSize, In))
+ return false;
+ clearerr(In);
+ // If the line contained null bytes, anything after it (including \n) will
+ // be ignored. Fortunately this is not a legal header or JSON.
+ size_t Read = std::strlen(&Out[Size]);
+ if (Read > 0 && Out[Size + Read - 1] == '\n') {
+ Out.resize(Size + Read);
+ return true;
+ }
+ Size += Read;
+ }
+}
+
+// Returns None when:
+// - ferror() or feof() are set.
+// - Content-Length is missing or empty (protocol error)
+llvm::Optional<std::string> JSONTransport::readStandardMessage() {
+ // A Language Server Protocol message starts with a set of HTTP headers,
+ // delimited by \r\n, and terminated by an empty line (\r\n).
+ unsigned long long ContentLength = 0;
+ std::string Line;
+ while (true) {
+ if (feof(In) || ferror(In) || !readLine(In, Line))
+ return llvm::None;
+ InMirror << Line;
+
+ llvm::StringRef LineRef(Line);
+
+ // We allow comments in headers. Technically this isn't part
+
+ // of the LSP specification, but makes writing tests easier.
+ if (LineRef.startswith("#"))
+ continue;
+
+ // Content-Length is a mandatory header, and the only one we handle.
+ if (LineRef.consume_front("Content-Length: ")) {
+ if (ContentLength != 0) {
+ elog("Warning: Duplicate Content-Length header received. "
+ "The previous value for this message ({0}) was ignored.",
+ ContentLength);
+ }
+ llvm::getAsUnsignedInteger(LineRef.trim(), 0, ContentLength);
+ continue;
+ } else if (!LineRef.trim().empty()) {
+ // It's another header, ignore it.
+ continue;
+ } else {
+ // An empty line indicates the end of headers.
+ // Go ahead and read the JSON.
+ break;
+ }
+ }
+
+ // The fuzzer likes crashing us by sending "Content-Length: 9999999999999999"
+ if (ContentLength > 1 << 30) { // 1024M
+ elog("Refusing to read message with long Content-Length: {0}. "
+ "Expect protocol errors",
+ ContentLength);
+ return llvm::None;
+ }
+ if (ContentLength == 0) {
+ log("Warning: Missing Content-Length header, or zero-length message.");
+ return llvm::None;
+ }
+
+ std::string JSON(ContentLength, '\0');
+ for (size_t Pos = 0, Read; Pos < ContentLength; Pos += Read) {
+ // Handle EINTR which is sent when a debugger attaches on some platforms.
+ Read = llvm::sys::RetryAfterSignal(0u, ::fread, &JSON[Pos], 1,
+ ContentLength - Pos, In);
+ if (Read == 0) {
+ elog("Input was aborted. Read only {0} bytes of expected {1}.", Pos,
+ ContentLength);
+ return llvm::None;
+ }
+ InMirror << StringRef(&JSON[Pos], Read);
+ clearerr(In); // If we're done, the error was transient. If we're not done,
+ // either it was transient or we'll see it again on retry.
+ Pos += Read;
+ }
+ return std::move(JSON);
+}
+
+// For lit tests we support a simplified syntax:
+// - messages are delimited by '---' on a line by itself
+// - lines starting with # are ignored.
+// This is a testing path, so favor simplicity over performance here.
+// When returning None, feof() or ferror() will be set.
+llvm::Optional<std::string> JSONTransport::readDelimitedMessage() {
+ std::string JSON;
+ std::string Line;
+ while (readLine(In, Line)) {
+ InMirror << Line;
+ auto LineRef = llvm::StringRef(Line).trim();
+ if (LineRef.startswith("#")) // comment
+ continue;
+
+ // found a delimiter
+ if (LineRef.rtrim() == "---")
+ break;
+
+ JSON += Line;
+ }
+
+ if (ferror(In)) {
+ elog("Input error while reading message!");
+ return llvm::None;
+ }
+ return std::move(JSON); // Including at EOF
+}
+
+} // namespace
+
+std::unique_ptr<Transport> newJSONTransport(std::FILE *In,
+ llvm::raw_ostream &Out,
+ llvm::raw_ostream *InMirror,
+ bool Pretty,
+ JSONStreamStyle Style) {
+ return llvm::make_unique<JSONTransport>(In, Out, InMirror, Pretty, Style);
+}
+
+} // namespace clangd
+} // namespace clang
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